The present invention relates generally to air conditioning systems and, more specifically, to a retrofit air conditioning system for use with an existing induction air conditioning system.
Currently, many older commercial and educational buildings employ an induction air conditioning system which supplies a mixture of fresh ventilation air and recirculated building air to individual rooms of the building. Typically, these systems provide means for heating the air, either centrally and/or locally, to provide conditioned air and, in some instances, have been modified to include means for cooling the air as well. Because the design for these induction systems dates back over 30 years, these systems do not meet the performance and efficiency requirements of today's new, more sophisticated air conditioning systems. A need therefore exists for a means to bring the performance and efficiency of these older, less efficient air conditioning systems up to current operating levels.
Solutions for improving existing induction systems have focused primarily on replacing a majority of the existing system with a new, more sophisticated air conditioning system and, as a result, have been costly. Because variable operating cost savings of a new system over an existing system do not quickly recover the initial cost, upgrading of existing systems has typically not been found to be cost-justified. This is particularly true for those existing induction systems employed in schools in Indiana where new systems have not been cost-effective due in part to the problems associated with modifying the existing building construction, such as the removal of asbestos and other additional system components.
Nevertheless, these existing induction systems do not meet the needs of today's schools. For example, to accommodate more students with minimal added expense, some school systems have adopted a twelve-month operating year employing staggered semesters. As such, both cooling and heating of air supplied to the individual school rooms is desired, and preferably, at minimal added expense.
One example of an existing induction system, employed in more than 300 Indiana schools, employs heating means for providing 70.degree. F. air to each room, wherein the conditioned 70.degree. F. air induces recirculation air from the room to supply a mixture of conditioned air and recirculated air into the room. Some of these existing systems, rather than being replaced, have been modified to cool the recirculated room air prior to mixing with the conditioned air. However, these modified systems are inefficient and represent significant operating cost increases for the school. Furthermore, the added restriction of cooling coils in the recirculated room air's path adversely affects the optimum balance of conditioned and recirculated air delivered to the room.
A need therefore exists for an improved air conditioning system adapted for replacing an existing induction air conditioning system. Such a system should provide both efficient cooling and heating of air to provide year-round comfort. Such a system should be compatible with an existing induction system to reduce the cost of implementation. Ideally, such a system would be a retrofit air conditioning system which utilizes as much of the existing induction system hardware as possible. Such a system should also be uniquely compatible with existing induction air conditioning systems currently installed in many school buildings to further reduce the cost of implementation.